In 1972, on a park bench in Birmingham, Ala., Garner Lee Green’s father proposed to her mother. The proposal came out of the blue. She said yes.

“That doesn’t happen to people anymore,” says Ms. Green, who is 30. And it certainly wasn’t the way her husband asked her to marry him several years ago. The two of them talked for a long time about how and when the proposal would happen. “I was ready before he was, so we had to come to a meeting of the minds about a time frame. The negotiations lasted about six months,” Ms. Green says.

She is not the only one who missed what used to be a classic big moment. Those romantic tales that get passed among friends and relatives—”One day he just showed up with a ring! I was completely surprised!”—are vestiges of the past. We’ve gone from popping the question to a long conversation, hammering out the details of when and how the engagement will happen.

It was a quick romance. We shopped for the ring together. And I knew exactly when he was going to propose. I was 24. The surprise came on a Tuesday night, three months after the ring. We broke up. Actually, he broke up.